string getString()
{
	return "just a test";
}
void test()
{
	const char* pc = getString().c_str();
	cout << pc << endl;
}
void test1()
{
	cout << getString().c_str() << endl;
}


int main()
{
	string greet("Hello, world");
	string hi(greet);
	char* ptr = (char*)hi.c_str();
	ptr[0] = 'h';
	cout << hi << endl;//hello, world 
	cout << greet << endl;//Hello, world 
	test1();//"just a test"
	test();//空字符

}